Just an observation on the user interface of mobile phone chargers. My phone runs flat all the time. And it's all UI.
The phone manual sayeth: "Do not leave the phone on the charger once it is charged; doing so will reduce battery life." The phone gives no signal when its charged.
So I have to stand over the phone when its charging, to ensure I unplug it appropriately.
As a result: I don't charge it when I'm in a rush; and it never gets charged when I'm about to do something else - I will forget it.
Blech. How much can a 'disconnect when charged' circuit really cost?